Study on Growth and Decline Law of Contagious Pleuro-pneumonia in Piglets

In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in the piglets borne by cows inoculated with A. pleuropneumonia vaccines （type I, II, and VII） before delivery was detected. The results showed that type I, II, and VII maternal antibodies in piglets decreased gradually with the age growing overall, and was at the critical protection value at the ages of 42-50 days （type I） and 28 days （type VII）, lower than the quantification rate; and the antibodies all turned to be negative until the ages of 70 days （type I）, 60 days （type VII） and 35 days （type II）. The first immunization should be carried out at the age of 42-50 days using type I A. pleuropneumonia vaccine, and at the age of 28 days using type VII A. pleuropneumonia vaccine. However, type II A. pleuropneumonia maternal antibody had lower level and positive rate and could not well protect piglets, so the various A. pleuropneumonia vaccines differed in the date for the first immunization. In order to achieve a better immunization effect, A. pleuropneumonia vaccines with different valences should be further researched and developed.

STRONG LAW OF LARGE NUMBERS AND GROWTH RATE FOR NOD SEQUENCES

In the paper,we get the precise results of Hájek-Rényi type inequalities for the partial sums of negatively orthant dependent sequences,which improve the results of Theorem 3.1and Corollary 3.2 in Kim(2006)and the strong law of large numbers and strong growth rate for negatively orthant dependent sequences.

Containment effort reduction and regrowth patterns of the Covid-19 spreading

In all countries the political decisions aim to achieve an almost stable configuration with a small number of new infected individuals per day due to Covid-19.When such a condition is reached,the containment effort is usually reduced in favor of a gradual reopening of the social life and of the various economical sectors.However,in this new phase,the infection spread restarts and,moreover,possible mutations of the virus give rise to a large specific growth rate of the infected people.Therefore,a quantitative analysis of the regrowth pattern is very useful.We discuss a macroscopic approach which,on the basis of the collected data in the first lockdown,after few days from the beginning of the new phase,outlines different scenarios of the Covid-19 diffusion for longer time.The purpose of this paper is a demonstration-of-concept:one takes simple growth models,considers the available data and shows how the future trend of the spread can be obtained.The method applies a time dependent carrying capacity,analogously to many macroscopic growth laws in biology,economics and population dynamics.The illustrative cases of France,Italy and United Kingdom are analyzed.

Balanced biosynthesis and trigger threshold resulting in a double adder mechanism of cell size control

How cells accomplish cell size homeostasis is a fascinating topic, and several cell size regulation mechanisms were proposed: timer, sizer, and adder. Recently the adder model has received a great deal of attention. Adder property was also found in the DNA replication cycle. This paper aims to explain the adder phenomenon both in the division-centric picture and replication-centric picture at the molecular level. We established a self-replication model, and the system reached a steady state quickly based on evolution rules. We collected tens of thousands of cells in the same trajectory and calculated the Pearson correlation coefficient between biological variables to decide which regulatory mechanism was adopted by cells. Our simulation results confirmed the double-adder mechanism. Chromosome replication initiation and cell division control are independent and regulated by respective proteins.Cell size homeostasis originates from division control and has nothing to do with replication initiation control. At a slow growth rate, the deviation from adder toward sizer comes from a significant division protein degradation rate when division protein is auto-inhibited. Our results indicated the two necessary conditions in the double-adder mechanism: one is balanced biosynthesis, and the other is that there is a protein trigger threshold to inspire DNA replication initiation and cell division. Our results give insight to the regulatory mechanism of cell size and instructive to synthetic biology.

Hybrid Cellular Automaton-Parabolic Thick Needle model for equiaxed dendritic solidification

A hybrid Cellular Automaton(CA)-Parabolic Thick Needle(PTN)model is developed for the simulation of an equiaxed dendritic grain.It is implemented by solving conservation equations with the Finite Element(FE)method at two scales.At the scale of the microstructure,dendritic branches are approximated by a network of PTN.The solute field is computed in the liquid using a FE mesh with minimum size smaller than the diffusion length ahead of the dendrite tips,giving access to a detailed description of each dendrite tip growth velocity as well as solutal interactions between branches.At the simulation domain scale,volume averaged heat and solute transfers are solved on a coarser FE mesh.The average volumetric fraction of phases is deduced from a field giving the fraction of dendritic microstructure together with a microsegregation model.Because the PTN themselves grow on CA cells,the dendrite tip growth velocity is transferred to the vertices of the polygon associated to the CA growth shape.Similarly,the field giving the fraction of dendritic microstructure is deduced from the fraction of CA cells part of the mushy zone,which include cells containing PTN network.Advantages of the new multiple scale CAPTN model include solutal interaction between dendrite branches together with long range transfer of heat and solute mass,together with the role of latent heat release on equiaxed solidification.